Field

Field features are great for entity enrichments from one-to-one or many-to-one relations. It is commonly used to enrich an entity with simple, non aggregate fields from related assets or entities.

Main use cases

1. Add a field feature from a data asset with the same level of granularity as the entity (one-to-one relationship)

2. Add a field feature from a related entity with one-to-one relationship

3. Add a feature from a parent entity (many-to-one relationship)

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Simple field feature

In this example, we define two simple field features for the entity customer:

# customer.yml
features: 

- type: field
  name: organization_size
  asset: db_prod.core.organizations
  field: size
  data_type: number
  filters: null
  
- type: field
  name: is_us_customer
  asset: db_prod.core.geos
  join_name: login_geo
  data_type: boolean
  field: iff(name = 'US', true, false)
  filters: null

type

The feature type. In case of field features, it should be set to field.

name

Give the field feature a name.

asset

The data asset with the field to be added as feature to our entity. asset should be the full path: "db.schema.name".

asset has to be related to our entity (see related data asset).

join_name [optional]

In case multiple join patterns are defined between an entity and a data asset, join_name is used to determine which join path to use for a specific feature.

In the example above, we are joining the entity customer to the geos asset using the login_geo join path name. For more information about using multiple join paths between an entity and a data asset, visit the related data assets page.

data_type [optional]

Specify the feature data type. If no data_type specified, Lynk will assume the data type is string.

The options for data types are:

string

For any type of string data type

number

For any type of number data type. For example: integer, float, decimal etc..

bool

For boolean data type.

datetime

For any type of time-based data type. For example: date, timestamp, datetime etc..

field

The name of the field we would like to get from the related asset, in order to enrich our entity.

field can be any SQL expression which does not include aggregate functions.

filters

Custom filters to be applied on the data asset. See filters page for in depth information on how to apply filters.

Understanding Field Features

In case we have a one-to-one relationship between a Data Asset and an Entity, and we need to enrich the entity with a field from the Data Asset - we can simply define which field to enrich the entity by.

To better understand how Field features work, look the following diagram;

Field Feature Diagram

The above diagram shows an example when a customer (entity) has one nation (data asset). That means, each customer can be associated with only one row in db.schema.nations.

In this case, we took the field nation_name , and added it to the customer entity as a feature.